Collapsible tubing



April 6, 1963 w. E. REJESKI 3,085,596

COLLAPSIBLE TUBING Filed Aug. 31. 1959 /a mum/for l/l ////0m E. Re eSk/By his af/omeys United States Patent 1 3,085,596 COLLAPSIBLE TUBINGWilliam E. Rejeski, Farmington, Conn., assignor to The Wiremold Company,West Hartford, Conn., a corporation of Connecticut Filed Aug. 31, 1959,Ser. No. 837,146 4 Claims. (Cl. 138-131) This invention relates tocollapsible two-element tubing made from strips of metal and fabric orother suitable flexible material capable of being wound helically incontinuous lengths of any desired dimension with the edges of themetallic and flexible spiral strips locked together.

The invention is an improvement on .the invention disclosed in the A. E.Chernack Patent 2,417,676 issued March 18, 1947.

It is an object of the invention to provide an improved construction ofcollapsible tubing which will permit much sharper or tighter bends thanheretofore without requiring additional material or more complicated ormore expensive construction.

A related object is to provide improved tubing construction having theabove-mentioned characteristics which also provides a smoother interiorsurface at the bend of the tubing than heretofore.

Other advantages of the invention will become apparent as it isdescribed in connection with the accompanying drawing.

In the drawing:

FIG. 1 is a side elevation view of tubing embodying the invention.

FIG. 2 is a fragmentary perspective View of the new tubing, partly insection, the section 'being taken by cutting the tubing along line 22 ofFIG. 1.

FIG. 3 is a section view of the bend in the tubing of FIG. 1 with thesection being taken by making a cut along line 3-3 of FIG. 1.

In collapsible tubing to which this invention relates, a metallic stripis continuously wound in spiral form on known machines. The edges of thestrip 10 are reversely bent outwardly to form flanges 12 and 14 whichare bent down toward the outer face of the strip upon edges of aflexible strip 18 of any suitable material. Treated or untreated textilefabric and plastic sheet materials are typical examples that arecommonly used, but the invention is not limited to such materials.

The edges of the metallic strip frictionally and securely hold the edgesof the flexible strip very firmly as the edges of the metal are bentdown upon and clamp the edges of the flexible strip between the flangesand the body of the metal strip.

Tubing of the sort thus far described has been used in large quantitiessatisfactorily for many years for many purposes. It has been made invarious diameters with strips of varying width. But one problem whichfor a long time has defied solution was the inability to bend the tubingin as tight bends as desired in many instances.

In many diameters of tubing, short lengths of tubing could be bent onlywith diflicul-ty even into a right angle bend due to the edges of eachmetal spiral being maintained in abutment with its neighbors with theflexible strip being folded inwardly. Thus, the dimensions of thefabricated metal spiral, together with the thickness of the flexiblestrip (two thicknesses being between each pair of abutting metal stripedges), imposed a definite limitation on the angularity of the bend towhich such tubing of any given diameter and any given width of metal andflexible strips could be bent. In short lengths, it was never possibleto bend the tubing into U-shape and fre quently it was impossible withinthe limited length avail- 3,085,596 I Patented Apr. 16, 1963 ice ablefor bending, to bend the tube at a sufficiently tight bend to satisfythe most advantageous requirements.

According to the present invention,provision is made for the spirals ofthe metal strip to fold upon one another within the inside curve as thetubing is bent. This not only enables more convolutions of the metalspiral to be put into a given arc, but also allows the fabric to foldinwardly and not to interfere with the folding over or overlapping ofthe metal spirals. This objective is accomplished by providing a slightbend 16 in the metal strip along its length parallel to the edges ofthat strip or, in other words, along or parallel to its longitudinalaxis. As a result of this angulation, one edge of the metal spiral isoffset outwardly slightly with respect to the other; or in other words,the arc of curvature of one edge of the metal strip is of greaterdiameter than the other edge of that strip.

The angle of the bend preferably is in the neighborhood of 30 from itsoriginal flat position or, referring to the oblique angle, in theneighborhood of This angle may vary consider-ably and is not critical.It is necessary only that the offset of the neighboring edges ofadjacent spirals of the metal strip be suflicient to allow the edges ofone convolution to fit under the adjacent edge of the next convolutionso that when the tubing is bent, the convolutions may nest together, asshown in FIGURE 3.

The offsetting and the folding or nesting together of the convolutionsallows the angularity of the bend to be at least double what heretoforewas possible with tubing having the same metal and flexible stripmaterials and the same dimensions and diameter. For example, a 16 inchlength of tubing of 4 inch diameter can now be bent into a complete Uand almost so that the opposite ends touch, in contrast to the bendingability heretofore being limited to not more than about a right anglefor tubing of the same size, length and materials.

In addition to the ability to bend the improved tubing into so muchtighter bends, the nesting of the metal spirals and the flexible stripresults in less of the flexible strip being forced into the tube and,hence, a smoother interior surface is provided with concomitantimprovement in fluid flow within the tubing.

Modifications within the scope of the invention will occur to thoseskilled in the art. Therefore, the invention is not limited to the exactform and dimensions illustrated and described.

What is claimed is:

1. A flexible tubing structure adapted for flex-ure into short radiusangular bends comprising a continuous metallic strip in helical formhaving edge and body portions, the edge portions being reversely bentand lying adjacent the body portion, a strip of flexible materialdisposed and clamped between the adjacent edge and body portions of eachadjacent convolution of said metallic strip, the body portion of saidmetallic strip being bent parallel to said edges throughout the lengthof said strip such that the diameter of one edge of the convolutionsformed by the metallic strip is greater than the diameter of theopposite edge thereof, the smaller diameter edge portion of eachconvolution being opposed by the larger diameter edge portion of thenext adjacent convolution whereby when said tube is bent to a maximumangle of curvature the larger diameter edge portions of each convolutionwill overlap the smaller diameter edge portions of each adjacentconvolution at the innermost radius of curvature and a minimal amount offlexible material is thereby folded into the interior of the tubing.

2. A flexible tubing structure adapted for flexure into short radiusangular bends comprising a continuous metallic strip in helical shape, ahelical strip of flexible material interposed between and affixed to theedges of the metallic 3 strip between each convolution thereof, saidmetallic strip having its edges displaced, one with respect to theother, such that the circumference of one edge of each convolution ofthe metallic strip exceeds the circumference of the other edge thereof,said strip and said flexible material in each convolution being soaflixed that the edge of the metallic strip having the smallercircumference will nest, when said tubing is bent to a maximum ofcurvature, Within the larger circumference of the next adjacentconvolution thereof at the innermost radius of curvature of 10 saidmetallic strip.

3. Flexible tubing structure as claimed in claim 2 wherein said edgeportions of said metallic strip are reversely bent toward the same faceof the body portion of the metallic strip.

4. Flexible tubing structure as claimed in claim 2 wherein said edgeportions of said metallic strip are reversely bent outwardly of thetubing and overlie the same face of the body portion of the metallicstrip.

References Cited in the file of this patent UNITED STATES PATENTS1,030,016 Rosenthal June 18, 1912 1,905,824 Dysthe Apr. 25, 19332,417,676 Chernack Mar. 18, 1947 2,841,183 Rejeski July 1, 1958

1. A FLEXIBLE TUBING STRUCTURE ADAPTED FOR FLEXURE INTO SHORT RADIUSANGULAR BENDS COMPRISING A CONTINUOUS METALLIC STRIP IN HELICAL FORMHAVING EDGE AND BODY PORTIONS, THE EDGE PORTIONS BEING REVERSELY BENTAND LYING ADJACENT THE BODY PORTION, A STRIP OF FLEXIBLE MATERIALDISPOSED AND CLAMPED BETWEEN THE ADJACENT EDGE AND BODY PORTIONS OF EACHADJACENT CONVOLUTION OF SAID METALLIC STRIP, THE BODY PORTION OF SAIDMETALLIC STRIP BEING BENT PARALLEL TO SAID EDGES THROUGHOUT THE LENGTHOF SAID STRIP SUCH THAT THE DIAMETER OF ONE EDGE OF THE CONVOLUTIONSFORMED BY THE METALLIC STRIP IS GREATER THAN THE DIAMETER OF THEOPPOSITE EDGE THEREOF, THE SMALLER DIAMETER EDGE PORTION OF EACHCONVOLUTION BEING OPPOSED BY THE LARGER DIAMETER EDGE PORTION OF THENEXT ADJACENT CONVOLUTION WHEREBY WHEN SAID TUBE IS BENT TO A MAXIMUMANGLE OF CURVATURE THE